How long before all streetlights in most areas are LED?

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Glenn A
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Re: How long before all streetlights in most areas are LED?

Postby Glenn A » Thu Jul 13, 2017 15:02

There are still a few concrete standards in Cockermouth with their charming sixties meat pie lanterns, but I notice the lanterns having some kind of tape around them which might indicate they're going LED.

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Re: How long before all streetlights in most areas are LED?

Postby Mark Hewitt » Thu Jul 13, 2017 15:05

I was thinking about this last night in terms of 'everyday things which are going', and outside at night we don't have the pervasive yellow glow that we used to have. Everything being deep orange is seems old fashioned already.

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Re: How long before all streetlights in most areas are LED?

Postby Glenn A » Thu Jul 13, 2017 15:33

Mark Hewitt wrote:I was thinking about this last night in terms of 'everyday things which are going', and outside at night we don't have the pervasive yellow glow that we used to have. Everything being deep orange is seems old fashioned already.

It used to be interesting on Tyneside all the orange street lights making the sky turn orange at night.

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Re: How long before all streetlights in most areas are LED?

Postby Bertiebus » Tue Aug 15, 2017 13:39

Glenn A wrote:
Mark Hewitt wrote:I was thinking about this last night in terms of 'everyday things which are going', and outside at night we don't have the pervasive yellow glow that we used to have. Everything being deep orange is seems old fashioned already.

It used to be interesting on Tyneside all the orange street lights making the sky turn orange at night.

Living somewhere with no streetlights but within a few miles of several towns, for the past few winters I have watched the ominous orange glow in the night sky turn gradually whiter and whiter each year. The light pollution is still there, it's just a different colour now. There are nights when the cloud is a certain height that it reflects the light back and I can easily see to walk without a torch.

I have always found the 'glow in the sky' caused by street lights unpleasant, but it was only when I moved to somewhere where there were none in the immediate vicinity that I realised quite how much I hate it. A clear night sky is a stunningly beautiful thing when you get the chance to see a properly dark one. I find the delicate, ethereal 'moon rainbows' particularly wonderful.

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Re: How long before all streetlights in most areas are LED?

Postby brummie_rob » Wed Aug 16, 2017 06:34

Bertiebus wrote:
Glenn A wrote:
Mark Hewitt wrote:I was thinking about this last night in terms of 'everyday things which are going', and outside at night we don't have the pervasive yellow glow that we used to have. Everything being deep orange is seems old fashioned already.

It used to be interesting on Tyneside all the orange street lights making the sky turn orange at night.

Living somewhere with no streetlights but within a few miles of several towns, for the past few winters I have watched the ominous orange glow in the night sky turn gradually whiter and whiter each year. The light pollution is still there, it's just a different colour now. There are nights when the cloud is a certain height that it reflects the light back and I can easily see to walk without a torch.

I have always found the 'glow in the sky' caused by street lights unpleasant, but it was only when I moved to somewhere where there were none in the immediate vicinity that I realised quite how much I hate it. A clear night sky is a stunningly beautiful thing when you get the chance to see a properly dark one. I find the delicate, ethereal 'moon rainbows' particularly wonderful.


I don't think LED has the light pollution that SON did. I noticed a certain area by me where they have just switched to LED, the unpleasant orange glow has gone, with a much more muted white colour, but you have to look harder to see it.

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Re: How long before all streetlights in most areas are LED?

Postby Helvellyn » Wed Aug 16, 2017 10:34

brummie_rob wrote:I don't think LED has the light pollution that SON did. I noticed a certain area by me where they have just switched to LED, the unpleasant orange glow has gone, with a much more muted white colour, but you have to look harder to see it.

Better reflectors perhaps? And the lack of colour probably makes the white harder to notice anyway, if it's not too bright. The downside from an astronomer's point of view is that at least the sodium lines are very narrow so can be filtered out without much loss elsewhere.

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Re: How long before all streetlights in most areas are LED?

Postby KeithW » Wed Aug 16, 2017 13:37

brummie_rob wrote:
I don't think LED has the light pollution that SON did. I noticed a certain area by me where they have just switched to LED, the unpleasant orange glow has gone, with a much more muted white colour, but you have to look harder to see it.


With SOX that is undoubtedly true but I am not convinced that is true of all SON installations. The house I lived in until 2015 was in an area where they replaced the orange SOX lanterns with white SON. Not only was the colour less intrusive but the light was much more directional and IMHO was a quite acceptable solution. It was something of a shock on moving house to find I had a SOX lamp at the end of the drive and the orange glow was back. Fortunately they got replaced by MUCH less intrusive LED lamps over the winter. I haven't measured it but the LED lamp looks to be emitting a fairly soft white light rather the the bluish actinic light associated with 5500 K LED's

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Re: How long before all streetlights in most areas are LED?

Postby Paianni » Wed Aug 16, 2017 14:19

Most LED fixtures are of cut-off designs, so no light escapes above the horizontal. That doesn't stop the light from reflecting off the road and into the sky, especially if it's wet. Full spectrum light poses an environmental issue as it simulates daylight, it can screw with melatonin levels in humans (this is why we shouldn't use smartphones at night) and any non-human habitats in urban areas.

SON cut-off is probably the sweet spot for residential roads, but only because it's impossible to find SOX cut-off for anything under 66W.

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Re: How long before all streetlights in most areas are LED?

Postby wrinkly » Wed Aug 16, 2017 16:58

I think SOX light pollution is the least bad for astronomers as it's a few frequencies.

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Re: How long before all streetlights in most areas are LED?

Postby Beardy5632 » Sun Sep 10, 2017 17:41

I've noticed it appearing more around the Forest of Dean over the last couple of months.
It looks like the SOX on the B4226 is going to be the next lot to bite the dust by the looks of things as the new lights have already been put up on the poles ready. It's a shame that those lot are going cos they've been there for as long as I can remember.
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Re: How long before all streetlights in most areas are LED?

Postby KeithW » Mon Sep 11, 2017 13:06

wrinkly wrote:I think SOX light pollution is the least bad for astronomers as it's a few frequencies.


That's pretty academic in reality. Serious optical astronomy is most done on mountain tops above the bulk of the atmosphere and most amateurs don't have the equipment to filter frequencies. Even when you do its a partial solution at best. Cambridge University still has its astronomical site on the Madingley Road but all the serious optical work is done overseas. The telescopes are now most used by students and they also have public observation nights. The last time serious reaearch work happened on site was in the 1930's.

As for LED street lights we had our SOX lamps replaced by LED's last winter. They are actually a great improvement as they are much more directional. I can sit out in my back garden and actually see many more stars now than used to be the case with the all pervading orange glow gone.

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Re: How long before all streetlights in most areas are LED?

Postby Berk » Tue Sep 12, 2017 00:08

KeithW wrote:
wrinkly wrote:I think SOX light pollution is the least bad for astronomers as it's a few frequencies.


That's pretty academic in reality. Serious optical astronomy is most done on mountain tops above the bulk of the atmosphere and most amateurs don't have the equipment to filter frequencies. Even when you do its a partial solution at best. Cambridge University still has its astronomical site on the Madingley Road but all the serious optical work is done overseas. The telescopes are now most used by students and they also have public observation nights. The last time serious reaearch work happened on site was in the 1930's.
So what is the Five Mile telescope used for?? Seems a bit of a waste of a former railway, really...

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Re: How long before all streetlights in most areas are LED?

Postby wrinkly » Tue Sep 12, 2017 00:15

Berk wrote:So what is the Five Mile telescope used for?? Seems a bit of a waste of a former railway, really...


Radio astronomy.

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Re: How long before all streetlights in most areas are LED?

Postby KeithW » Tue Sep 12, 2017 12:54

Berk wrote:
KeithW wrote:
wrinkly wrote:I think SOX light pollution is the least bad for astronomers as it's a few frequencies.


That's pretty academic in reality. Serious optical astronomy is most done on mountain tops above the bulk of the atmosphere and most amateurs don't have the equipment to filter frequencies. Even when you do its a partial solution at best. Cambridge University still has its astronomical site on the Madingley Road but all the serious optical work is done overseas. The telescopes are now most used by students and they also have public observation nights. The last time serious reaearch work happened on site was in the 1930's.
So what is the Five Mile telescope used for?? Seems a bit of a waste of a former railway, really...


I rather made a point of specifying optical astronomy, the Five Kilometre (not Mile) telescope was at the Mullard Radio Astronomy which sort of gives the game away. There were mobile and fixed radio telescopes operating in the 2 GHz band. You could shine a searchlight on them and they would not care. I say was because the original array no longer operates and the hardware has been repurposed as the Arcminute Microkelvin Imager. It studies galaxy clusters by observing radio signals with frequencies between 12 and 18 GHz,

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Re: How long before all streetlights in most areas are LED?

Postby Paianni » Tue Sep 12, 2017 15:40

KeithW wrote:
wrinkly wrote:I think SOX light pollution is the least bad for astronomers as it's a few frequencies.
As for LED street lights we had our SOX lamps replaced by LED's last winter. They are actually a great improvement as they are much more directional. I can sit out in my back garden and actually see many more stars now than used to be the case with the all pervading orange glow gone.
That's not an evaluation of the light source, more the luminaire design. Cut-off SON would be preferable for light pollution as the sky glow is far reduced compared to LED, whilst retaining the same advantages.

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Re: How long before all streetlights in most areas are LED?

Postby KeithW » Tue Sep 12, 2017 19:25

Paianni wrote:
KeithW wrote:
wrinkly wrote:I think SOX light pollution is the least bad for astronomers as it's a few frequencies.
As for LED street lights we had our SOX lamps replaced by LED's last winter. They are actually a great improvement as they are much more directional. I can sit out in my back garden and actually see many more stars now than used to be the case with the all pervading orange glow gone.
That's not an evaluation of the light source, more the luminaire design. Cut-off SON would be preferable for light pollution as the sky glow is far reduced compared to LED, whilst retaining the same advantages.


White light is what it is and doesn't reflect off wet surfaces any differently because of the way it is generated. I see a great reduction of sky glow now the the SOX has gone. That orange glow used to pervade every room at the front and side of the house. At most what I have now is rather like moonlight. The only complaints reported in this area have been that its not bright enough, personally I would be happy if they turned it off between midnight and dawn.

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Re: How long before all streetlights in most areas are LED?

Postby Paianni » Thu Sep 14, 2017 15:11

KeithW wrote:
Paianni wrote:
KeithW wrote:As for LED street lights we had our SOX lamps replaced by LED's last winter. They are actually a great improvement as they are much more directional. I can sit out in my back garden and actually see many more stars now than used to be the case with the all pervading orange glow gone.
That's not an evaluation of the light source, more the luminaire design. Cut-off SON would be preferable for light pollution as the sky glow is far reduced compared to LED, whilst retaining the same advantages.


White light is what it is and doesn't reflect off wet surfaces any differently because of the way it is generated. I see a great reduction of sky glow now the the SOX has gone. That orange glow used to pervade every room at the front and side of the house. At most what I have now is rather like moonlight. The only complaints reported in this area have been that its not bright enough, personally I would be happy if they turned it off between midnight and dawn.
You misread one of my earlier posts; all light reflects off wet surfaces in the same way, it's just that the output of white LEDs creates far greater skyglow than SOX, SON or even incandescent lights, using the Bortle Dark-Sky scale. The main contributor to this is wavelengths in the 'blue' part of the spectrum. The light distribution of the luminaire makes no difference. SOX light does have a related advantage, as explained by Matthew Eagles: "Low-pressure sodium light is safer for driving in rain as the light remains sharp and unblurred. This is because white light consists of various colours, which undergo varying degrees of refraction and diffusion as they pass through water vapour or ice crystals; in contrast, SOX light is monochromatic."

The aesthetics of white light are subjective, from a technical perspective the output of SOX fulfills most sane outdoor lighting requirements to a greater extent than what most other light sources are capable of.

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Re: How long before all streetlights in most areas are LED?

Postby Mark Hewitt » Thu Sep 14, 2017 15:34

Paianni wrote:Most LED fixtures are of cut-off designs, so no light escapes above the horizontal. That doesn't stop the light from reflecting off the road and into the sky, especially if it's wet. Full spectrum light poses an environmental issue as it simulates daylight, it can screw with melatonin levels in humans (this is why we shouldn't use smartphones at night) and any non-human habitats in urban areas.


Isn't that taken care of my the likes of 'night shift' on the iPhone - the way I have mine set it goes to a nighttime mode after 7pm, which basically removes most of the blue from the screen.

My home lighting does the same, it's 'daylight' during the day then transitions to a much more yellowish light in the evening.

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Re: How long before all streetlights in most areas are LED?

Postby KeithW » Thu Sep 14, 2017 16:05

Paianni wrote:
You misread one of my earlier posts; all light reflects off wet surfaces in the same way, it's just that the output of white LEDs creates far greater skyglow than SOX, SON or even incandescent lights, using the Bortle Dark-Sky scale. The main contributor to this is wavelengths in the 'blue' part of the spectrum. The light distribution of the luminaire makes no difference. SOX light does have a related advantage, as explained by Matthew Eagles: "Low-pressure sodium light is safer for driving in rain as the light remains sharp and unblurred. This is because white light consists of various colours, which undergo varying degrees of refraction and diffusion as they pass through water vapour or ice crystals; in contrast, SOX light is monochromatic."

The aesthetics of white light are subjective, from a technical perspective the output of SOX fulfills most sane outdoor lighting requirements to a greater extent than what most other light sources are capable of.


Actually the Bortle Dark Sky scale says nothing about the origin of the light apart from when you get to level 7 or 8 . Level 8 stipulates

the sky is light gray or orange – one can easily read
stars forming familiar constellation patterns may be weak or invisible
M31 and M44 are barely glimpsed by an experienced observer on good nights
even with a telescope, only bright Messier objects can be detected
limiting magnitude with 12.5" reflector is 13


In my neighbourhood with SOX lights emitting in all directions and the orange glow reflecting from clouds I would have rated as an 8. Only the very brightest stars were visible and I could not see any constellations.

With the current LED setup I would rate it at Bortle 4 to 5. While the street in front of my house is reasonably well lit my back garden is now dark enough to go stargazing and can see all the major constellations in that direction. In fact I now need a flashlight to safely find my way around the garden if the house mounted floodlight is off. If you think SOX light meets most sane outdoor lighting requirements I can only assume you do not value colour vision. Nobody I know who put lights outside their house opted for SOX. They either went Halogen, CFL or LED. You seem to be in a minority in this regard.

Of course if you want to do better than Bortle scale 4 you need to ban ALL outdoor lighting which is not a vote winner in urban areas. In fact as I mentioned before the only complaints raised with our local councillor about the new lighting is that they would have liked it to be brighter.

As for on the road I have been driving since 1971 and would strongly assert that the main cause of glare in wet weather is car headlights, street lighting is a secondary effect at best except in so far as people tend to dip their headlights in town.

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Re: How long before all streetlights in most areas are LED?

Postby Paianni » Thu Sep 14, 2017 16:20

KeithW wrote:In my neighbourhood with SOX lights emitting in all directions and the orange glow reflecting from clouds I would have rated as an 8. Only the very brightest stars were visible and I could not see any constellations.

With the current LED setup I would rate it at Bortle 4 to 5.
Glare from a deep bowled luminaire will reduce the ability to see any light dimmer than it in the background. Nothing to do with skyglow though, and the reduction in the lumens output of the replacement LEDs was also a factor. Your judgement could have easily been influenced by a confirmation bias.

Most of the lights in my county switch off at 12-midnight (except the LED-lit A-roads) and the 'orange glow' doesn't go away, it comes from a range of sources, mainly London.


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